The invention relates to a method and apparatus for monitoring the production of products wherein a chemical transformation takes place during production, as well as monitoring quality control, wear, and other physical properties.
Ultrasonic sensors, and particularly Piezo Electric sensors are used extensively in industry as warning devices, for example as a proximity sensor to detect when someone is getting too close to machinery, and as pressure sensing devices for mapping the contact pressure profile between two objects, such as Tekscan ultrasonic sensors. Characteristics of ultrasonic sensors are well recognized by those skilled in the art.
Ultrasonic sensors may comprise contact sensors, such as a shear wave transducer, or non-contact sensors, such as longitudinal wave transducers. In the prior art, when it is considered that ultrasonic sensing is needed, it has been the practice that those skilled in the art determine the kind of sensor that would give them the best results, and then use the sensor for that one, specific purpose.
A method for monitoring the state of a rubber used to make a rubber or rubber composite product at all stages of development comprises the steps of: (a) using an ultrasonic sensor comprising a shear wave transducer, using a frequency of 500 kHz to 20 MHz to monitor uncured rubber compound for deviation from a standard; (b) using said shear wave transducer having a frequency of 500 kHz to 20 MHz to monitor the state of cure the rubber in a shaped rubber product or rubber composite; and (c) using a longitudinal wave ultrasonic sensor having a frequency of 500 kHz to 20 MHz to measure the properties of cured rubber in a rubber product or rubber composite.
The method may comprise measuring viscoelastic response of a cured rubber or rubber composite at more limited frequencies such as 500 kHz to 5 MHz.
The method may comprise the step of monitoring flaw development in a composite.
In a further aspect of the invention, an apparatus for monitoring the condition of a rubber or a rubber composite comprises: (a) a contact ultrasonic sensor having a frequency of 500 kHz to 20 MHz to monitor uncured rubber compound for deviation from a standard; (b) a contact ultrasonic sensor having a frequency of 500 kHz to 20 MHz to monitor the state of cure of rubber in a shaped rubber product or rubber composite; and (c) an air coupled ultrasonic sensor having a frequency of 500 kHz to 20 MHz to measure the properties of cured rubber in a rubber product or rubber composite.
In an illustrated embodiment of the apparatus, an air medium is used for the longitudinal wave transducer.
In an illustrated embodiment, the signals of the ultrasonic sensors have a 1 MHz central frequency.